High-powered optical sources have many applications in which an intense beam of light is focused onto a substrate or other target. In many high-power optical source architectures, a signal from a seed source is fed into an optical amplifier that amplifies the power of the signal. One example, among others, of such a high-power optical source architecture is referred as a master oscillator, power amplifier (MOPA) architecture. The MOPA architecture allows precise pulsing of the amplified output. Laser systems based on optical amplification of seed signals are often used in high power applications, such as laser micromachining.
Many high power optical systems make use of wavelength conversion to produce light having a desired wavelength or range of wavelengths. Often the process of conversion involves performing some non-linear optical wavelength conversion on input light from a source, such as a MOPA source. Conventional fiber MOPA system typically cannot support high peak powers for pulse widths longer than about 1.7 ns. For example, U.S. Pat. No. 7,039,076 to Kane et al. describes limitations on peak power for a fiber amplifier system as a function of pulse width. As seen from FIG. 1, peak power decreases abruptly as pulse width increases above about 1.7 nanoseconds. In addition, the use of a passively Q-switch master oscillator, as described in U.S. Pat. No. 7,039,076 offers limited flexibility to vary pulse repetition rate and pulse width. However, there are a number of applications involving both MOPA architecture and wavelength conversion that could benefit from longer pulse durations.
It is within this context that embodiments of the present invention arise.